How Gut Microbes Influence Stress Resilience: A Biological Perspective

Emerging research has highlighted the connection between gut microbiota and stress resilience, unveiling some of the unique ways in which our microbial inhabitants can shape our psychological responses to stress. We’ve known that the gut microbiome is a community of trillions of bacteria in the gastrointestinal tract and that it plays a pivotal role in maintaining mental health by influencing neurobiological mechanisms that regulate stress responses [3].

Stress triggers a cascade of biological reactions, activating the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the release of stress hormones like cortisol. Chronic stress can lead to dysregulation of this axis, resulting in mental health disorders such as anxiety and depression [9]. Recent studies suggest that gut microbiota may help modulate this response, promoting stress resilience through various pathways.

One key mechanism by which the gut microbe influences stress resilience is through the production of metabolites that impact brain function. For instance, short-chain fatty acids (SCFAs), produced by the fermentation of dietary fibers by gut bacteria, have been shown to exert neuroprotective effects. 

In a study led by Dr. Arpana Church, co-director of UCLA’s Microbiome Center, researchers examined the gut microbiomes of 116 adults to understand how gut health relates to psychological resilience. Participants underwent psychological assessments to evaluate their resilience, defined as their ability to cope with stress [6]. The findings indicated that individuals with higher resilience exhibited specific metabolites and gene activity in their microbiomes that correlated with better emotional regulation and cognitive function.

Moreover, resilient individuals showed reduced inflammation and improved gut barrier integrity, suggesting a healthier microbiome composition. This aligns with previous research emphasizing the bidirectional relationship between the brain and gut, where dysfunction in one can lead to issues in the other. Dr. Church noted, “If you think about stress, it’s almost equal to smoking five cigarettes per day.”

The gut microbiome can also influence the body’s inflammatory response, which is closely linked to stress. Chronic inflammation has been implicated in the pathogenesis of stress-related disorders. One study found that individuals with a more diverse gut microbiome exhibited lower levels of inflammatory markers, suggesting that a healthy microbiota may confer protective effects against stress-induced inflammation [7]. This relationship underscores the importance of maintaining a balanced microbiome for overall mental health and resilience.

The gut-brain axis plays a critical role in this interaction. Gut microbes communicate with the central nervous system through the vagus nerve, a key component of the parasympathetic nervous system. Research indicates that stimulation of the vagus nerve could enhance stress resilience by modulating the gut microbiota composition [8]. This bidirectional communication highlights the potential for dietary and lifestyle interventions aimed at improving gut health to foster resilience to stress.

Furthermore, specific dietary patterns have been linked to gut microbiome diversity and stress resilience. A diet rich in whole foods, fiber, and fermented products has been associated with a more diverse microbiome, which is thought to be beneficial for mental health [5]. Conversely, diets high in processed foods and sugars have been shown to negatively impact gut microbiota diversity, potentially increasing vulnerability to stress and related disorders [1]. Dr. Church emphasizes that individuals can influence their gut health through dietary adjustments, recommending a diverse diet rich in fiber and fermented foods, aiming for at least 30 different fruits and vegetables per week to support microbiome diversity.

In conclusion, the growing body of evidence underscores the critical role of gut microbiota in shaping stress resilience. Through the production of metabolites, modulation of inflammation, and communication with the brain, gut microbes can significantly influence our psychological responses to stress. As research continues to unravel these connections, it becomes increasingly clear that promoting a healthy gut microbiome through diet and lifestyle may be a promising strategy for enhancing mental health and resilience against stress. 

Reviewed By: Emily Walsh

Designed By: Allison Chin

References: 

[1] Aggarwal, N., Kitano, S., Puah, G. R. Y., Kittelmann, S., Hwang, I. Y., & Chang, M. W. (2023). Microbiome and Human Health: Current Understanding, Engineering, and Enabling Technologies. Chemical reviews, 123(1), 31–72. https://doi.org/10.1021/acs.chemrev.2c00431

[2] Bercik, P., Denou, E., Collins, J., Jackson, W., Lu, J., Jury, J., Deng, Y., Blennerhassett, P., Macri, J., McCoy, K. D., Verdu, E. F., & Collins, S. M. (2011). The intestinal microbiota affect central levels of brain-derived neurotropic factor and behavior in mice. Gastroenterology, 141(2), 599–609.e6093. https://doi.org/10.1053/j.gastro.2011.04.052

[3] Brestoff, J. R., & Artis, D. (2013). Commensal bacteria at the interface of host metabolism and the immune system. Nature immunology, 14(7), 676–684. https://doi.org/10.1038/ni.2640

[4] Cheng, J., Hu, H., Ju, Y., Liu, J., Wang, M., Liu, B., & Zhang, Y. (2024). Gut microbiota-derived short-chain fatty acids and depression: deep insight into biological mechanisms and potential applications. General psychiatry, 37(1), e101374. https://doi.org/10.1136/gpsych-2023-101374

[5] Dahiya, D. K., Renuka, Puniya, M., Shandilya, U. K., Dhewa, T., Kumar, N., Kumar, S., Puniya, A. K., & Shukla, P. (2017a). Gut microbiota modulation and its relationship with obesity using prebiotic fibers and probiotics: A Review. Frontiers in Microbiology, 8. https://doi.org/10.3389/fmicb.2017.00563

[6] Davis, K., & Flatow, I. (2024, October 14). How gut microbes are linked to stress resilience. Science Friday. https://www.sciencefriday.com/segments/gut-microbiome-stress-resilience/

[7] Gill, P. A., Inniss, S., Kumagai, T., Rahman, F. Z., & Smith, A. M. (2022). The role of diet and gut microbiota in regulating gastrointestinal and inflammatory disease. Frontiers in Immunology, 13. https://doi.org/10.3389/fimmu.2022.866059

[8] Kraimi, N., Lormant, F., Calandreau, L., Kempf, F., Zemb, O., Lemarchand, J., Constantin, P., Parias, C., Germain, K., Rabot, S., Philippe, C., Foury, A., Moisan, M. P., Carvalho, A. V., Coustham, V., Dardente, H., Velge, P., Chaumeil, T., & Leterrier, C. (2022). Microbiota and stress: a loop that impacts memory. Psychoneuroendocrinology, 136, 105594. https://doi.org/10.1016/j.psyneuen.2021.105594

[9] Ulrich-Lai, Y. M., & Herman, J. P. (2009). Neural regulation of endocrine and autonomic stress responses. Nature Reviews Neuroscience, 10(6), 397-409.

Throwback Edition: The Intersection of Traditional Medicine, Indigenous Foods, and Bioethics

Millenia-old activities are making their return in health and wellness. As modern healthcare continues to evolve, interest is growing to integrate traditional, cultural, and Indigenous medical practices and dietary systems into the mainstream. This intersection of traditional and contemporary medicines and habits presents potential opportunities. However, we must be careful not to get too ahead of ourselves and carefully consider the ethical issues surrounding this intersection.

Indigenous communities, no matter their location, have consistently relied on traditional plant-based remedies and food sources that have roots deep within their beliefs [1]. These traditional systems are often holistic and focus on maintaining balance and harmony between the individual, community, and natural environment, for example traditional Chinese medicine. Similarly, the food practices of these communities emphasize their relationship with the land they inhabit— utilizing local, seasonal, and minimally processed ingredients [2]. 

In recent decades, there has been an increased scientific interest in exploring the health benefits of traditional herbal medicines and Indigenous foods, because they are natural and provide more healthy alternatives to modern drugs [3]. This interest is what has mainly fueled the desire to integrate these approaches into contemporary practices and guidelines. However, the appropriation and commercialization of this knowledge without the consent and participation of the communities it comes from raises significant ethical concerns [4].  

One key dilemma is the issue surrounding intellectual property rights and fair distribution of the material benefits derived from traditional medicine and food systems. Indigenous communities possess large repositories of ecological knowledge and applications, which could be of great value to pharmaceutical, nutraceutical, and food industries. But these communities have historically been exploited, with their resources being removed without proper recognition, compensation, or even partnerships [5]. This practice of “biopiracy”, or unauthorized use of biological resources and traditional knowledge, has worsened the trust between Indigenous populations and corporations and in turn marginalized Indigenous populations, who witness this exploitation with nothing in return. 

In addition, the attempted integration of these medicines and foods into clinical care and health initiatives has to be approached with cultural sensitivity and respect for traditional beliefs and practices. Insensitive integration can result in the degradation of traditional knowledge, the disruption of community well-being, and further marginalization [6]. Further, ignorant use of these traditional herbal remedies in a clinical setting can pose a danger: a lack of understanding  their cultural importance or potential side effects with conventional medicine undermines the efficacy and safety of the treatment.

By navigating the ethical issues that stem from integrating traditional medicine and foods with modern efforts, healthcare systems can be more inclusive and culturally responsive to health and wellness. One successful example of this approach is the development of the Traditional Medicine Program at the Waiwai Health Center in New Zealand. This program was a partnership of the local Māori community and the regional health authority, which allowed for the use of traditional Māori healing practices and native medicinal plants alongside conventional medical treatments [7]. 

With an increasingly globalized world, it becomes crucial to bridge the gap between traditional and modern medicine. By working through the ethical considerations surrounding this combination of Indigenous medicine and foods with current approaches, healthcare systems can become more holistic and equitable in their work.

Edited By: Anna Chen

References 

[1] Shankar, D., Nanda, A., & Bhandari, K. K. (2020). The need for integration of traditional and modern medicine. Journal of Ayurveda and integrative medicine, 11(1), 1-3.

[2] Kuhnlein, H. V., & Receveur, O. (1996). Dietary change and traditional food systems of indigenous peoples. Annual review of nutrition, 16(1), 417-442.

[3] Bodeker, G., & Burford, G. (2007). Traditional, Complementary and Alternative Medicine: Policy and Public Health Perspectives. London, UK: Imperial College Press.

[4] Buchanan, A., & Keohane, R. O. (2006). The legitimacy of global governance institutions. Ethics & International Affairs, 20(4), 405-437.

[5] Reardon, J., & Cycon, D. (2019). Eradicating Biopiracy. Environmental Law, 49(4), 1-55.

[6] Lavallee, L. F., & Poole, J. M. (2010). Beyond recovery: Colonization, health and healing for Indigenous people in Canada. Qualitative health research, 20(5), 695-707.

[7] Durie, M. (1999). Mental health and Māori development. Australian & New Zealand Journal of Psychiatry, 33(1), 5-12.

Nutritional Inequities in Prisons: Investigating the Link Between Prison Food and Mental Health

The connection between food and mental health may not always seem apparent, but it is significant– particularly within incarcerated populations. Individuals in prison often face elevated rates of mental and behavioral health issues [1]. Research reveals a strong correlation between diet and mental health, showing that proper nutrition supports both physical and mental well-being. Balanced meals with proteins, protein, carbohydrates, and fats help produce neurotransmitters that assist in regulating mood and emotions. Without the necessary nutrients found in a healthy meal, one can be more prone to conditions such as “depression, anxiety, irritability, and cognitive impairment” [2].

This issue is especially relevant in prisons, where food quality is often poor, unhealthy, and even degrading for inmates. Junk food and spoilage are common, with three out of four formerly incarcerated individuals reporting rotten food on their trays [3].  For a population already experiencing poor mental health, these substandard food options may exacerbate existing issues.

It is important to note that about 95% of incarcerated people are released, so their mental health is not just a personal concern but rather a community concern [3]. Providing inmates with nutritious and proper meals aligns with an ethical obligation to treat all individuals with respect and dignity, and will improve outcomes for incarcerated people in the long run. Improving the nutritional quality of prison food could have far-reaching benefits, supporting inmates’ mental health both during and after incarceration. This shift would promote not only individual well-being but also a healthier, more resilient community as formerly incarcerated individuals reintegrate into society. 

Reviewed By: Radhika Subramani

References: 

[1] Mommaerts, K., Lopez, N. V., Camplain, C., Keene, C., Hale,  A. M., & Camplain, R. (2023). Nutrition availability for those incarcerated in jail: Implications for mental health. International journal of prisoner health, 19(3), 350–362. https://doi.org/10.1108/IJPH-02-2022-0009

[2] Mass General Brigham McLean. “Diet and Mental Health: How Nutrition Shapes Your Well-Being.” Putting People First in Mental Health , 24 May 2024, www.mcleanhospital.org/essential/nutrition. 

[3] Soble, L., Stroud, K., & Weinstein, M. (2020). Eating Behind Bars: Ending the Hidden Punishment of Food in Prison. Impact Justice. impactjustice.org/impact/food-in-prison/#report